There is known a technology in which the color of an image printed on a paper (sheet) with decolorable material (toner or ink) is erased by a decoloring apparatus, and it becomes possible to reuse paper through this technology.
However, the paper will damage due to the repeated decoloring operation. Then the damaged paper may cause a paper jam in the decoloring apparatus or in the image forming apparatus.
Conventionally, the decoloring apparatus prints a mark (reuse mark) representing a decolored times on the paper every time a decoloring processing of an image is carried out.
The reuse mark is read by a scanner, and the decoloring apparatus discharges the paper to a reject tray in a case in which the decoloring times is greater than a given times according to the read value of mark. Alternatively, if it is determined that the paper can hardly be reused because the media is broken, the decoloring apparatus discharges the paper to the reject tray.
However, on the paper discharged to the reject tray, there is no module (mark) used to identify that it is the paper that has already been discharged in the reject tray other than the reuse mark, the user may sometimes mistake the paper as the reusable paper at first glance. Thus, it is afraid that the user may use a paper the decolored times of which is greater than a given times again.